An 8-minute Self-Paced Cycling Test designed for endurance fitness monitoring: Cross-sectional validity, test–retest reliability, and practical implementation

Monitoring cycling fitness remains challenging. Most submaximal tests rely on physiological responses to imposed workloads and overlook perceptual responses. This study evaluated the cross-sectional convergent validity and test–retest reliability of the Self-Paced Cycling Test (SCT-RPE), an 8-minute rating of perceived effort (RPE)-regulated protocol. Twenty-one cyclists completed the SCT-RPE, comprising three 2-minute stages at RPE Moderate, Strong, and Very strong, followed by recovery and a 6-second sprint (Ppeak). Power output-to-heart rate ratios (PO/HR) and weighted indices (wPO/HR) were calculated at stage and overall levels. Validity was evaluated against graded exercise test outcomes and sprint performance, and reliability across repeated trials. wPO/HRoverall was retained as a candidate endurance-fitness index because it showed a strong association with peak work rate (Wpeak, R2 = 0.77, p < 0.001, slope = 13.4 W per unit), acceptable reliability, and power-dominant weighting aligned with the RPE-regulated design. Endurance-related variables showed moderate-to-very-high interday reliability (intraclass correlation coefficients, ICC3,1 = 0.72–0.94; coefficients of variation of the typical error, CVTE = 3.29%–7.97%). Ppeak showed high reliability (ICC3,1 = 0.86; CVTE = 8.96%) and an almost perfect correlation with sprint performance (r = 0.93). The SCT-RPE showed cross-sectional convergent validity and acceptable reliability; longitudinal responsiveness remains to be established.